They identified a group of genes responsible for odour compounds called volatile sulfur compounds, and found that these genes become highly activated as the fruit ripens, driving its unusual smell.

“The durian smell has been described as a mix of an onion-like sulfury aroma with notes of sweet fruitiness and savory soup-seasoning. A key component of the durian smell are volatile sulphur compounds, or VSCs, which have been characterised as decaying, onion-like, rotten eggs, sulfury and fried shallots,” said geneticist Bin Tean Teh, deputy director of the National Cancer Center Singapore, co-leader of the study published in the journal Nature Genetics.

Unlike other plant species that typically have one or two copies of these genes, this species boasted four copies, demonstrating that VSC production is, as Teh put it, “turbocharged” in durian fruits.

The researchers said this odour may be important to the durian in the wild, helping to attract animals to eat it and disperse its seeds.

This file photo taken on July 14, 2015 shows a vendor peeling open a durian fruit at a roadside shop in Karak, in the suburbs of Pahang outside Kuala Lumpur. AFP

The scientists sequenced the genome of the Musang King variety of durian, discovering it has about 46,000 genes, nearly double the number in the human genome.

They were able to trace the evolution of the fruit back 65 million years, finding an ancient relationship to the cacao tree, whose seeds produce chocolate.

“Most of us in Singapore have grown up with the durian, and we are very familiar with it,” said geneticist Patrick Tan, a professor at Duke-NUS Medical School in Singapore. “However, even within the same family, there are individuals that love the taste, while others have learned to simply tolerate it, especially during durian season. For those who have never experienced durian before, it can indeed elicit opposing emotions of devotion and revulsion.”

Durian is eaten fresh, cooked, fermented or as an ingredient in candies, baked goods and other food.

The researchers said there are at least 30 other durian species, some edible, some inedible, and some with other distinctive features. Several are endangered.

Durian is economically important, with imports to China last year worth US$600 million to US$800 million, the researchers said. --REUTERS